It is important that aircraft maintain a correct course during all stages of flight, including during takeoff roll on a runway. To perform the takeoff roll properly, the aircraft generally accelerates on the runway within an envelope of course and acceleration. The course limits include, for example, the ability to stay in, or nearly in, the center of the runway. A departure outside of this envelope can result in an undesirable positioning of the aircraft with respect to the runway.
In some instances visibility may be poor during takeoff operations, resulting in what is known as instrument flight conditions. During instrument flight conditions, pilots rely on instruments, rather than visual references, to navigate the aircraft. Even during good weather conditions, pilots may rely on instruments to some extent during the takeoff. Some airports and aircraft include runway assistance positioning systems, for example a localizer, to help guide aircraft during takeoff operations. These systems allow for the display of a lateral deviation indicator to indicate aircraft lateral deviation from the departure course.
Current takeoff operations under low visibility conditions are limited by runway visual range limits (RVR). If the RVR is below these limits, the takeoff is not allowed (the pilot must be able to immediately return for a landing if an emergency occurs). A localizer signal may be used under low RVR to avoid deviations from the departure (runway) heading. However, a localizer for assisting pilots during takeoffs has limitations, for example, the necessity to maintain the localizer sensitivity area clear and many airports do not provide a localizer adequately positioned for departure.
Accordingly, it is desirable to provide additional guidance to the pilot by an enhanced vision system when a reliable localizer is not available, thereby improving the ability to fly low visibility takeoffs from a larger number of airports. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.